Ministry of Forests and Range Inventory Projection

Variable Density Yield Prediction - WinVDYP 1.1 and Batch VDYP 6.6

Table of Contents

• What is VDYP
• Registration
• About the Release of VDYP
  • Download User Guides Now
• Installation
• System Requirements
• Installation Instructions
• Overlay Data Sets
• References for Site Index Function Enhancements
• Software Support
• Addendum:   Re-compiled VDYPBAT.EXE 

What is VDYP

The Variable Density Yield Prediction (VDYP) is an empirical yield prediction system for natural stands, based upon temporary inventory sample and permanent growth sample data. The model predicts stand heights, diameters, volumes and mean annual increments at different utilization levels and ages. VDYP uses the ‘Air Method’, which uses crown closure as the density measure.

VDYP software contains the VDYP model and has two main components, interactive and batch. Interactive VDYP (WinVDYP) is an easy to use tool designed to predict yields, one stand at a time. Batch VDYP is designed to process many stands at a time with much less user intervention, and is run via a command line containing either 'FIPUPDATE', which completes Forest Inventory Planning (FIP) files, or 'BATCHPROCESS', which generates yield curves. Both WinVDYP and Batch VDYP use the same core modules and configuration files when calculating yields.

Registration

Recipients of VDYP via the TIB homepage are encouraged to register themselves at the time of software download. This will enable us to keep you better informed of further software developments.

About  this Release of VDYP

This release of WinVDYP 1.1 and Batch VDYP 6.6d offers the following enhancements (over WinVDYP 1.0 and Batch VDYP 6.4a).

Software

Core Modules: a new site index function has been adopted for hemlock in the interior of the province as described by Nigh (1997b). In addition maple now uses the cottonwood site index function (Thower & Assoc., 1992); previously the alder function was used (Harrington and Curtis, 1986).

Configuration Files: No changes have been made.

WinVDYP: new core modules used; bug fixed which occasionally prevented the entry of species percents to a tenth of a percent; dates and version numbers changed in the yield tables and the help facility.

Batch VDYP: new core modules used; a Y2K fix has been made to FIPUPDATE such that ages are now correctly projected when reference year is 2000 or greater.

User Guides

• Both the WinVDYP and Batch User Guides have been updated to reflect changes to the core modules, version numbers and release dates.

Download User Guides Now

• Batch User Guide self extracting zipped file pdf format
• WinVDYP User Guide self extracting zipped pdf format

Installation

System Requirements

Before installing VDYP, please ensure that your computer meets the following minimum requirements:

• 4 MB of random access memory (RAM), 8 MB of RAM recommended
• Intel 386 processor or better, however 486 or Pentium is highly recommended
• Windows 3.1, Windows for Workgroups 3.11, Windows 95, Windows NT or Windows 98 operating environment
• 10 MB of free disk space on your hard drive

If any of these conditions do not hold, you still may be able to install and run VDYP but performance may be affected.

Installation Instructions

(Installation drive assumed to be C:\)

1. Create a temporary directory called VDYPINST.
2. Download VDYP.EXE (2.8 Mb) to your computer and save it in the temporary directory.
3. From Windows Explorer, double click on the file with your mouse. VDYP.EXE is a self extracting zipped file and will automatically unzip into the following four files:

• setup.a02
• setup.arv
• setup.exe
• setupmn.arv

4. Ensure that all Windows applications are shut down.
5. From Explorer, double click on the file SETUP.EXE in your temporary directory.
6. When prompted for the permanent installation directory, specify the desired location (e.g., C:\VDYP) and click on the "Continue" button.
7. Once all files have been installed, you have the option of having the installation program automatically create a VDYP Group within your Program Manger. Click on the "Create" button to have this happen.
8. You have completed the process when the installation complete window appears. Click on the "OK" button to finish.
9. To save disk space, you can now erase the VDYP install software in your temporary installation directory.

Overlay Data Sets 

The following table lists the overlay data sets (Version 2.0) that have currently been made available on the internet by Resources Inventory Branch for use with WinVDYP. These data sets consist of growth and yield sample data and can be displayed within WinVDYP graphs as a check of yield validity.

When unzipped, file sizes range from 5 to 11 megabytes.

Notes:

To obtain these files in unzipped format:

• Download them from the internet to your computer
• unzip the files (into the same directory) by double clicking your mouse on the file in the File Manager

The overlay files, once unzipped, that can be used directly by WinVDYP (there is no need to further convert these files using the import feature of the software).

The interior temporary sample plots have been divided by leading species because of the large number of samples in the overall grouping. The multiple overlay feature of WinVDYP will allow you to display these files together on one graph if you so wish.

See the 'Using Graphs' section of the WinVDYP's help facility for instructions on how to display the information of interest in these files

Need to re-process FIP files locally

Since the provincial roll-over in 1994, when FIP files where initially created, enhancements to site index functions have been made to the core modules of VDYP. These changes will impact FIP file completion, using FIPUPDATE, when polygons contain the following species:

coast-FIZ = A,B,C ; interior-FIZ=D,E,F,G,H,I,J,K,L

As a result of these changes, site index values and projected attributes (e.g. height) and yields (e.g. volumes, diameters) may be out-of-date in FIP files that have not been processed using the most current software. RIB management have agreed that it is not feasible for RIB staff to re-process all affected FIP files with each site index function change. Clients have therefore been requested to re-process files locally, if required, on a priority basis using FIPUPDATE either as a stand alone application of embedded within FCAP3.4

Height Projection Bug:

At the time release, a bug was detected in the core modules caused by a benign change to the site index derivation code.  This resulted in projected heights being set to 0.0 whenever site index was calculated to be less than or equal to 1.3 meters.  A query of FIP data revealed that this bug would have negligible impacts - less than 100 scattered polygons (within TSAs) were impacted provincially, the vast majority of which were alpine forest types (with larch leading) for which volumes are not calculated.  This small impact coupled with a pressing release deadline and other factors prompted the decision to defer a fix until a subsequent release of VDYP.

References for site index function enhancements

Alberta Forest Service. 1985. Alberta phase 3 forest inventory: yield table for unmanaged stands. ENR Rep. No. Dep. 60a.

Barker, John E. and J.W.Goudie. 1987. Site index curves for Sitka spruce. B.C. Min. For., Res. Branch, Victoria, B.C.

Goudie, James W. 1984. Height growth and site index curves for lodgepole pine and white spruce and interim managed stand yield tables for lodgepole pine in British Columbia. B.C. Min. For, Res Br. Unpubl. 75p.

Harrington, C. and R. Curtis. 1986. Height growth and site index curves for red alder. U.S. Dep. Agric. For. Serv. Res. Pap. PNW-358. 14p.

Nigh, G. 1997a. A Sitka spruce height-age model. B.C. Min For. Res. Branch. Unpubl. Rep. 31 p.

Nigh, G. 1997b. A system for estimation of height and site index of western hemlock in the interior of British Columbia. B.C. Min For. Res. Branch (draft manuscript).

Thrower J. and Associates Ltd. 1992. Height age/site-index curves for Black Cottonwood in British Columbia. B.C. Min. For. Inv. Branch 92-07-IB. 21p.

Wiley, K. 1978. Site index tables for western hemlock in the Pacific Northwest. Weyerhaeuser Co. For. Res. Cent. For. Pap. 17. 28p

Software Support

WinVDYP is supported by Research Branch extension staff. Support for Batch VDYP, when used as a stand alone application, continues to be offered by Forest Analysis and Inventory Branch. The manuals and on-line help give the specific support staff.

Addendum

Re-compiled VDYPBAT.EXE

Subsequent to this release of VDYP a processing error has infrequently been encountered when running FIPUPDATE from the DOS command prompt of Windows. This resulted in the premature termination of the program and generation of the following message:

‘Floating point error: Stack fault. Unhandled exception’.

The input FIP file on your command line will remain intact, but the output file will only contain records processed up to this error.

A fix has now been made by simply re-compiling the same Batch VDYP source code using different compiler settings that optimize the use of the registers that caused the problem.

If you experience this error please download the re-compiled VDYPBAT.EXE (dated 00/02/16) and use it to replace the original executable (dated 99/09/28) in your VDYP directory. Because the same source code has been used the FIPUPDATE version number (6.6 d) that is written to the FIP file version record remains the same; however the processing information that appears in your log file or screen display will now read:

VDYP Batch Program

Version: Prod 6.6d4, Feb 16 2000

There have been no reports of impacts to WinVDYP or BATCHPROCESS. FIPUPDATE running under a UNIX operating system has also not been affected.